Polymer concrete is a composite material which is based on a polymer containing a high amount of filler material, being a highly filled system with a minimum amount of an organic binder. Polymer concrete composite materials can be used in indoor and outdoor applications, for example, as electrical insulation systems in various electrical installations.
Polymer concrete is distinct from the generally used electrical insulation systems based on hardened epoxy resin compositions by its comparatively high filler content. Electrical insulation systems based on hardened epoxy resin compositions can, for example, be filled to about 65% by weight with filler material, for example with silica particles, wherein the average particle size distribution of the silica can be within the range of from 1 micron (μm) to 100 micron (μm), corresponding to an average particle size distribution of 10−3 mm to 10−1 mm. Polymer concretes can, for example, be filled to about 80% by weight or more with an aggregate of different filler sizes. It is this high filler content which gives the low material costs since the filler can generally be less than a third of the price of the polymeric component, for the same weight.
A filler content of about 65% in epoxy insulation systems can be the maximum amount of filler that is reasonably processable using a single filler particle size and yielding a non-porous material. Polymer concrete uses an aggregate of filler particle sizes to achieve higher filler contents whilst still yielding a non-porous material. U.S. Pat. No. 4,210,774 discloses an electrical insulation system formed of a polymer binder highly filled with graded inorganic filler particles, including an excess of 85% of such filler particles and wherein the polymer used can include methyl methacrylate. U.S. Pat. No. 4,210,774 states that epoxy resin systems are employed at lower filling levels and that epoxy resins are not suitable for the high filling levels disclosed in U.S. Pat. No. 4,210,774 because of the high viscosity and cost without providing corresponding dielectric strength (col. 5, lines 26f).
Known processing methods for polymer concrete materials can be unsuitable for the high volume manufacture of complex geometries and insert arrangements. For example, the rapid wear of flexible molds can preclude the careful control of surface quality and dimensions of the final part. At best they can be suited to the manufacture of simple insulators in applications where these properties are less of a concern.